Electrical apparatus



C. G. SMITH M 3 1933' ELECTRICAL APFYARATUS Re. 18,846

Original Filed July 30, 1923 Reiacued May UNITED STATES" PATENT OFFICE,

CHARLES G. SMITH,OF MEDFORD, MASSACIIUETTS ASSIGNOR BY MESNE ASSIGN- MENTS, TOBAYTHEON, INC; F CAMBRIDGE, MASSACHUSETTS, A CORPORATION OF MASQACHUSEITS I Original at. 1,714,402, dated Ma 21, 939, Serial no. 654,041, filedl'uly so,

reissue filed. may 21, 1931. Serial No. 539,120.

C The present invention relates to electrical apparatus and is more particularly concerned with a type of apparatus involvin electrlcal conduction through a gaseous me ium.

The-object of this invention is to provide a ga'seou's conduction apparatus in which the electrical characteristics of the discharge may be readily controlled g 1 It will'be bvious toflthose skilled in" the art that it is desirable to be ableto control the discharge of'a gaseous conduction device, particularlyf'for use in connection with the am-. plification or production of electrical osc1lla-. tions; Heretofore these operations have been carried out ordinarily by the used thermionic tubes involving. the employment of a heated filament, a construction which is generally fragile and expensive. According to thepresent invention, the gaseous discharge is caused to take place between non-incandescent electrodes and is controlled by deflecting electrons from their normal paths through the gaseous region. This construction obviates the use of an incandescent filament with its attendant batteries and other disadvantages. 1

In the drawing; illustrating the preferred form 'ofthe invention, Fig. 1 is an elevation in section of the improved gaseous conduction apparatus; Fig. 2 is a sectional plan view of the apparatus shown in Fig; 1; and Fig. 3 is a diagram of the improved apparatus employed in a circuit for the amplification of electrical oscillations. a

As a basis for thepresent invention it is preferred to use the type of apparatus disclosed in the copending patent of Smith, No. 1,545,207, filed August 8, 1920, patented July 7, 1925. This application discloses a novel form of insulating device comprising a pa-ir of electrodes spaced apart in a gas a distance which is short and comparable to the mean 'free path of the electrons in the gas, that is a distance such that electrons traveling directly across the gas space between the electrodes produce insuflicient ionization to initiate sub stantial conduction, the mean free path of the electrons being understood to be the average distance traversed by the electrons without ionizing impact with gas molecules (or ELECTRICAL APPARATUS 1923. Application for one of the electrodes in a manner to allow the passage of electrons therethrough with con-. sequent opportunity for them to traverse long paths and ionize a sufficient number of gas molecules to cause conduction to take place. This conduction is effectively controlled by a third electrode having portions adjacent the slots and so located that a positive potential applied to the third electrode attracts electrons 'theretoand diminishes their paths to such an extent that ionization is reduced. The illustrated embodiment of the invention comprises a receptacle 7 of glass or other insulating material having immersed therein a pair of concentric cylindrical electrodes 9 and 10 the distance between opposmg electrode surfaces'being short and com parable to the mean free path. The electrodes are supported at each end upon suitable insulating forms 15 and 16 maintained in the receptacle. According to the invention disclosed in the patent previously referred to,.these insulating forms are so constructed that all paths for electrical conduction between the electrodes through the insulating supports are too long to permit of breakdown. The inner electrode 10 is pro-' vided with a plurality of longitudinal slots 12 extending between the supports 15 and 16. A third electrode for the control of the gaseous discharge comprises a series of fins 20 arranged radially and adjacent electrode 10 near the slots. It is preferable to mold the fins 20 directly in the support 16, a process which is readily carried out if the supportsare formed of bakelite or similar material. The fins are connected by suitable wires indicated at 25 preferably embedded in the insulation. Suitable lead wires 17 18 and 19 are attached to the electrodes 9, 10 and 20 and sealed into the glass receptacle in the manner shown. In the particular construction shown, electrode 9 normally 'func tions as the cathode .and lOasthe anode; Upon applying a potgntial difference between anode 1 0 and,cathode 9, electrons are. forced between the electrodes. There is no. possibility of discharge directly between the opposing surfaces of the electrodes because I/ the electron paths which extend directly be-- impelled through the slots and impinge upon r tween such'surfaces are too short to allow a 0 sufiicient number of collisions with gas mole cules to initiate ionizationand conduction. owever, a large number of electrons'are "the inner surface of the a ode. Their paths are thus made sufliclently long to allow of theformation of positive ions in the region enclosed by the anode. The positive ions so formed are drawn by the electric field to the cathode, where they liberate additional electrons, thereby "initiating cumulative ionization. If now electrode 20.is made positive with respect the anode 10, a number of the electrons will be drawn toward electrode 20, thereby curtailing their. paths sufiicient- ,ly to reduce the conducting properties of thedevice as a whole, The number of electrons drawn to. the auxiliary electrode and the effect upon other electron'paths in the region are dependent upon the magnitude of the positive potential applied to the aux iliary electrode, and accordingly any cur-- rents which may be caused ,to fiow-upon'the application of a potential difference between electrodes 9 and 10 will vary in amplitude according to the potential applied to electrode 201 v I A 1 This eflect of controlling the gaseous dis- I charge by means of an auxiliary electrode is capable of embodiment in a number of syscation of electrical oscillations.

tems having great practical application. as for example in connectionv with the amplifi-' I Such an amplifying circuit is illustrated in Fig? 3, showing an input circuit consisting of, an

inductance 30 and a condenser 31 connected directly between electrodes 10 and 20. The inductance 30 may be -conveniently coupled ,to a wireless receiving antenna a carrier wave telephone systein, or any other source of high frequency alternations. Between the cathode 9 and anode 1 0 are connected a batany desired frequency depending upon the constants of escooperating circuits.

J The invention having been described, what is claimed is:

1. An electrical apparatus comprising a gas filled receptacle, ,immer'sedthereini and having opposing sur-. faces separated by distances which are too short to normally permit of'gaseous ionization and conduction, one of the electrodes. be-- providedwith openin to permit ofiong a cathode and an anode electron paths therethrough, and electrostatic means other than said electrodesiadjacent the openings for altering the'len hened-pathsin a manner to controlthe gaseo discharge.-

2. An electrical apparatus comprisin a receptacle filled with gasfa cathode 1mmersed therein, an anode having a plurality of slots and havingsurfaces spaced from'tlre surface/of the cathode a distance of the order of magnitude of the mean free path of elec- 1 trons in the gas, and electrostatic means adj acent said slots for controlling the passage of electrons through the openings in the anode. s 3. An electrical apparatus comprising agas filled receptacle, acathode, an anode hav;

ing a plurality of slots and having surfaces spacedjrom the cathode a distance of the order of magnitude of the mean free-path of electrons in the gasi,?and .agthi rd'electrode consisting of a plurality of connected fins spaced adjacent the slots in the anode for the purpose of controlling the trons between the anode-and cathodei 4. In gaseous conduction apparatus comprising electrically copperating' cathode and anode electrodes spaced apart a distance which normally insulates, one of the elec-' trodes beinghollow and having inside and outside conducting surfacesand the other electrode being opposite one of said surfaces, and a third control other of said surfaces. c e

' '5. A; gaseous conductionjdevice compris ing a sealed vessel containing an ionizable gas, and a pair of main electrodes having exelectrode opposite the assage of elecloo tended surfaces disposed opposite each other i" 5 within a distance of the order of themean free path of electrons in the gas, one of said electrodes having perforations for efiectin conduction of electricity through the body 0 gas between said electrodes, barrier means adjacent said electrodes for. preventing elec@ trons of the discharge from entering paths outside said perforations that are suflicient- -ly long toproduce ionization and gaseous conduction between said electrodes under the potentials applied thereto during operation,

and an additional electrode disposed adjacent one of said electrodes within a distance, inhibiting ionization of the gas the'rebetween to control the conduction inlthe space between said main electrodes upon variation of the tpotaential applied to said additional elecm e.

6. A gaseous conduction device comprising a sealed vessel containing an ionizable gas, a pair of main electrodes having extended electrode surfaces disposed opposite each other within a distance too short to permit gaseous ionization by the potential therebetween, one of said electrodes having perforations for eflecting conduction of electricity through the body of gas between said electrodes, barrier means adjacent said electrodes for blocking ionization of gas along all paths outside said perforations that are sufiiciently long to produce ionization and gaseous conduction between said main electrodes under the potentials applied therebetween during operation, an additional electrode disposed adjacent to one of said electrodes within a distance inhibiting ionization of the gas therebetween to vary the conduction of electricity through the body of gas between said main electrodes upon variation of the potential a plied to said additional electrode.

7. gaseous conduction device comprising a sealed vessel containing an ionizable gas, a pair of tubular electrodes surrounding each other and spaced apart within a distance of the order of the mean free path of electrons in the gas, one of said electrodes having perforations for effecting conduction of electricity through the body of gas between said electrodes, barrier means ad acent said electrodes for blocking ionization of gas along all paths outside said perforations that are sufliciently long to produce ionization and gaseous conduction between said main electrodes under potentials applied therebetween during operation, and an additional electrode mounted adjacent to one of said electrodes within a distance inhibiting ionization of the gas therebetween by potentials applied thereto, to vary the conduction of electricity through the gas between said main electrodes upon variation of the otential applied to said additional electrodb.

In testimony whereof, I have hereunto subscribed my name this 19th day of May, 1931.

CHARLES G. SMITH. 

